What do bats do in the dark? Biologist Elisabeth Kalko has spent the last ten years at Barro Colorado Island, looking for answers to that question. Using a combination of modern technology and old-fashioned field observation, Kalko has made some astonishing discoveries about how bats use echolocation to identify and catch prey. Kalko's work studying bats in the tropical forest and interpreting bat calls will tell us more about these fascinating creatures of the night.

How often have you heard someone say, "I'm as blind as a bat!" Bats are the subject of many popular misconceptions and false information; people are both fascinated and repelled by them. No matter how much bats are disliked, they are under-appreciated. As major predators of insects, bats are beneficial and essential to the balance of nature. A common brown bat can devour 600 mosquitoes in one hour!

How much do you know about these creatures of the night?

True or False:

Bats are blind.

Bats are rodents.

Bats are the only flying mammal.

Some species of bats are threatened.

Bat droppings (guano) are used to make some antibiotics.

Bats cause a high percentage of rabies cases.

Answers:

False; many bats have poor vision; they are active at night and have developed a keen sense of sound; one suborder of bats uses sight and smell to find food.

False; bats belong to the order Chiroptera; rodents like the paca belong to Rodentia.

True.

True; over 50% of American bat species are in severe decline or endangered.

True.

False; most of the fatal cases of rabies in the U.S. are caused by rabid dogs; bats very rarely bite those who handle them.

Elisabeth Kalko, seen on Frontiers, captures, identifies and tracks some of the more than 70 species of bat on Barro Colorado Island as they hunt for fish, fruit and insects. She uses a "bat detector" to convert bat calls so she can hear them.

Bats that use echolocation gauge distance by sending high-frequency, ultrasonic calls (as pulses) and measuring the time it takes for the reflected pulses to return (echo + location). Signals reflected back can also provide information on the type and size of a prey item. Humans can't hear many of the signals bats generate. Bat calls can range from low frequencies (9kHz) to very high frequencies (greater than 200kHz).

The game of Marco Polo is a little bit like echolocation. Can you make up a game that demonstrates echolocation? For example, one game might designate one person as the bat and other people in the group as various "prey" (frogs, fish, insects), each with its own audible code. The bat is blindfolded and has to locate each of its prey by sound. (Another kind of game might be modeled on the game Battleship. "Prey" use codes to designate their locations and the "bat" has to find them.)